190 HOFMEISTEB, ON 



The hinder end of the spermatozoon is frequently drawn 

 out into a narrow prolongation, but this is not a constant 

 character. It arises probably from the fact that during 

 the parting asunder of the spermatozoon and its mother-cell, 

 the plastic substance of the spermatozoon remains attached 

 to the membrane of the latter cell, and is mechani- 

 cally drawn out into a thin filament, which eventually 

 breaks on . 



The first division of the primary cell of an archegonium 

 can only be seen by means of careful transverse sections of 

 the prothallium made perpendicularly to its surface. The 

 cell divides into an inner and an outer daughter-cell by 

 means of a septum parallel to the free outer surface. The 

 former becomes the central cell of the archegonium — the 

 embryo-sac. At a later period it is the place of formation 

 of the embryo. The neck of the archegonium is produced 

 by the multiplication of the outer cell (PI. XXV, figs. 1, 2). 

 This cell protrudes outwardly, and is divided into two 

 daughter- cells by a septum strongly inclined to the surface 

 of the prothallium, and often almost perpendicular to it. 

 This septum is sometimes at right angles to a plane passing 

 through the longitudinal axis of the prothallium., sometimes 

 it forms an acute angle with that plane, and sometimes it 

 is parallel to it. One of these positions is as frequent as 

 the others. The larger of the two daughter-cells is divided 

 anew hj a septum super-imposed upon the latter septum, and 

 inclined in an opposite direction. The two-surfaced wedge- 

 shaped apical cell then divides from four to ten times by 

 means of septa inclined in different directions (PL XXV, 

 fig. 2). With this process the longitudinal growth of the 

 organ terminates. Each of the cells of the second degree — 

 which cells originate in the division of the apical cell by a 

 septum parallel to one of the lateral surfaces — divides im- 

 mediately after its production, by means of a longitudinal 

 septum radiating from the axis of the archegonium. The 

 neck of the archegonium consequently consists of four 

 parallel longitudinal rows of cells. Each of the cells con- 

 tains a lenticular nucleus, lying close to the cell-wall, and 

 from which strings of granular protoplasm radiate. Gran- 

 ules of a firm consistence are dispersed throughout the 



